“Certainly, I have not been sent to curse anyone but rather, I have been sent as a mercy.”[1]
The Prophet salallahu alayhi wa salam was once asked, “Ya Rasulullah! Invoke a curse upon the polytheists.” It was upon this request that he exclaimed, “Certainly, I have not been sent to curse anyone but rather, I have been sent as a mercy.”
The Prophet salallahu alayhi wa salam was sent with the hardest mission in a time which people were delved into the darkness of ignorance. It was important for him to gather support and this was done largely by his beautiful characteristics and merciful nature towards people. Once the Prophet salallahu alayhi wa salam was displeased but rather than hollering and cursing he showed compassion and forgiveness. It is about this Allah Ta'ala says in the Qur’an, “It was a mercy of Allah that you were soft and gentle with them. If you were rude, harsh, hard hearted, then they would have fled away from you.” (3:159)
This hadith indicates that we should not invoke curses on anyone, rather we should be tolerant. In our day and age, we are unfortunately pressurised that we must accommodate people who enjoying calling other Muslims 'kaafir' and 'munafiqs', it is important for these people to take a step back and recognise exactly what type of person Rasulullah salallahu alayhi wa salam was.
The tongue tends to move very quickly but we should try our best not to wish bad upon anyone, even in states of deep anger and displeasure. Tolerance is truly a great characteristic; whomsoever has the ability to develop it within himself should do so.
This hadith also indicates that the impression given off from a Muslim should be one of compassion, towards Muslims and non Muslims.
[1] Adabul Mufrad: Hadith #332